#include "bits/stdc++.h"
 
using namespace std;
typedef long long ll;

void solve() {
    int n, k;
    cin >> n >> k;
    vector<int> v(n);
    for (auto &x : v) {
        cin >> x;
    }

    ll sum = accumulate(v.begin(), v.end(), 0LL);
    ll ans = 1e18;

    for (int i = 0; i < k; i++) {
        int j = i;
        ll cur = 0;
        while (j < n) {
            cur += v[j];
            j += k;
        }
        ans = min(ans, sum - cur);
    }

    cout << ans << '\n';
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int t = 1;
    // cin >> t;
    while (t--) {
        solve();
    }
}